Merge branch 'master' of https://github.com/SDWebImage/SDWebImage into 5.x

# Conflicts:
#	SDWebImage/SDWebImageDownloader.m

SDWebImage/SDWebImageDownloader.h

@@ -183,6 +183,28 @@ typedef SDImageLoaderCompletedBlock SDWebImageDownloaderCompletedBlock;
  */
 - (nullable NSString *)valueForHTTPHeaderField:(nullable NSString *)field;
 
+/**
+ * Creates a SDWebImageDownloader async downloader instance with a given URL
+ *
+ * The delegate will be informed when the image is finish downloaded or an error has happen.
+ *
+ * @see SDWebImageDownloaderDelegate
+ *
+ * @param url            The URL to the image to download
+ * @param completedBlock A block called once the download is completed.
+ *                       If the download succeeded, the image parameter is set, in case of error,
+ *                       error parameter is set with the error. The last parameter is always YES
+ *                       if SDWebImageDownloaderProgressiveDownload isn't use. With the
+ *                       SDWebImageDownloaderProgressiveDownload option, this block is called
+ *                       repeatedly with the partial image object and the finished argument set to NO
+ *                       before to be called a last time with the full image and finished argument
+ *                       set to YES. In case of error, the finished argument is always YES.
+ *
+ * @return A token (SDWebImageDownloadToken) that can be used to cancel this operation
+ */
+- (nullable SDWebImageDownloadToken *)downloadImageWithURL:(nullable NSURL *)url
+                                                 completed:(nullable SDWebImageDownloaderCompletedBlock)completedBlock;
+
 /**
  * Creates a SDWebImageDownloader async downloader instance with a given URL
  *

SDWebImage/SDWebImageDownloader.m

@@ -171,7 +171,15 @@ static void * SDWebImageDownloaderContext = &SDWebImageDownloaderContext;
     return value;
 }
 
-- (nullable SDWebImageDownloadToken *)downloadImageWithURL:(NSURL *)url options:(SDWebImageDownloaderOptions)options progress:(SDWebImageDownloaderProgressBlock)progressBlock completed:(SDWebImageDownloaderCompletedBlock)completedBlock {
+- (nullable SDWebImageDownloadToken *)downloadImageWithURL:(NSURL *)url
+                                                 completed:(SDWebImageDownloaderCompletedBlock)completedBlock {
+    return [self downloadImageWithURL:url options:0 progress:nil completed:completedBlock];
+}
+
+- (nullable SDWebImageDownloadToken *)downloadImageWithURL:(NSURL *)url
+                                                   options:(SDWebImageDownloaderOptions)options
+                                                  progress:(SDWebImageDownloaderProgressBlock)progressBlock
+                                                 completed:(SDWebImageDownloaderCompletedBlock)completedBlock {
     return [self downloadImageWithURL:url options:options context:nil progress:progressBlock completed:completedBlock];
 }